This invention relates to a steam boiler for use in a furnace that may be coal fired, oil fired, or using other conventional fuels including particularly combustible refuse and trash typical of municipal collection centers. Steam boilers are an efficient means of converting bulk fuel into usable energy. Using boilers to supply steam engines or steam turbines, the heat energy of the fuels can be conveniently converted to mechanical work, which may subsequently be converted to electrical energy. Modern boiler and furnace designs have evolved to a highly efficient state. Typically, the boiler design utilizes an overhead water storage drum connected to a lower base storage drum by a multiplicity of selectively bent tubes. The arrangement of the upper and lower drums and the tubes is integrally related to the design of the furnace combustion chamber. Furthermore, the tube and drum arrangement and the furnace design is usually adapted for a specific type of fuel. For example, a boiler system utilizing coal would be designed differently than a system utilizing petroleum oil or gas as its fuel.
In achieving the high efficiencies of modern boiler and furnace designs, there has been a sacrifice of not only versatility but also ease of repair. A primary cause of boiler failure is the bursting or leaking of one or more of the many tubes interconnecting the upper and lower drums. Replacement of these tubes is extremely difficult because of the attachment of both ends of the tubes to displaced drums. Since the tubes are welded or in lower temperature systems brazed to the respective drums, selective replacement involves not only carefully separating the defective tube from the drums but difficult tasks of inserting, aligning, and welding the replacement tube to the drums.
In many situation, it is not necessary to achieve the high efficiencies that conventional boilers are achieving. The reasons may be varied. Boiler and furnace may be located in an area in which there are plentiful supplies but skilled technicians are unavailable. Or, the fuel being used in the furnace either is variable, that is consisting of different materials at different times, as is the nature of refuse and trash always inconsistent, burning at different temperatures and intensities. In these situations, a boiler that is dependable, heavy-duty, and easily repaired is preferable to one that is highly efficient but lacking in these other more mundane qualities. Also as important as the performance of the boiler is the capital investment involved. The boiler devised in this invention is designed to provide a moderately efficient boiler which is easily repairable and has a low initial capital cost and can operate in an unsophisticated furnace which is designed to utilize variable and different fuels.
The single drum boiler design of this invention basically sacrifices a degree of efficiency for substantial benefits in convenience and reduced capital cost.